There is only one file type that uses the .WXN extension:
Waixing Famicom Game ROM
A WXN file is a Famicom or Nintendo Entertainment System (NES) game ROM that has been encrypted for security purposes. It contains an encrypted duplicate of the game data originally stored in the Famicom or NES cartridge. WXN files can be decrypted into .NES ROM files, which can then be used by an NES emulator, such as Nestopia or Snes9x, to be played on a computer.
The Nintendo Entertainment System was previously known as Famicom, or Family Computer, when it was released in Japan in 1983. It became NES two years later, in 1985, when it was released in North America. Waixing is a Chinese company that created games for the Famicom (NES) system. They created some unlicensed knockoff games for the Famicom (NES) system, as well.
Updated: February 1, 2018